1
718
F. Orsini et al.
LETTER
yields increase in the latter medium: the maximum gap References and Notes
between the two media was observed with the most lipho-
(
1) (a) Sinou, D. Adv. Synth. Catal. 2002, 344, 221.
b) Lindstroem, U. M. Chem. Rev. 2002, 102, 2751.
2) Maryanoff, B. E.; Reitz, A. B. Chem. Rev. 1989, 89, 863.
philic aldehyde (n-octanal). In all cases the E isomer was
the major product; however, the E/Z ratio depended on
both the medium and the substrate.
(
(
(3) Broos, R.; Anteunis, M. Synth. Commun. 1976, 6, 53.
(
4) (a) Russel, M. G.; Warren, S. Tetrahedron Lett. 1998, 39,
995. (b) Russel, M. G.; Warren, S. J. Chem. Soc., Perkin
Concluding, we have developed a mild and efficient ‘one-
pot’ Wittig protocol, which works well in water at room
temperature, and even better in the presence of sodium
dodecyl sulfate, especially when the lipophilicity of the
carbonyl compound increases.
7
Trans. 1 2000, 505.
(
5) Sieber, F.; Wentworth, P. Jr.; Toker, J. D.; Wentworth, A.
D.; Metz, W. A.; Reed, N. N.; Janda, K. D. J. Org. Chem.
1999, 64, 5188.
(
(
6) Villieras, J.; Rambaud, M.; Graff, M. Tetrahedron Lett.
To widen the scope of this new protocol, work is in
progress to test semistabilized ylides, other surfactants
1985, 26, 53.
7) Wu, J.; Zhang, D.; Wie, S. Synth. Commun. 2005, 35, 1213.
(
cationic, non-ionic) and complex substrates, potentially
(8) Dambacher, J.; Zhao, W.; El-Batta, A.; Anness, R.; Jiang,
precursors of bioactive compounds.
C.; Bergdahl, M. Tetrahedron Lett. 2005, 46, 4473.
9) Dwars, T.; Paetzold, E.; Oehme, G. Angew. Chem. Int. Ed.
(
2005, 44, 7174.
(
10) Phosphonium dodecylsulfate was isolated from a blank
reaction performed as reported below in the absence of the
base and of the electrophile: ethyl a-bromo acetate (0.5
mmol) was added, under stirring, to a solution of SDS (0.05
Typical Procedure for Reactions in Water
In open atmosphere, tri-n-butylphosphine (247 mL), was added at
r.t. to a stirred solution of ethyl a-bromo acetate (1.0 mmol) in
deionized H O (1.0 mL). After 5 min aldehyde (1.1 mmol) was add-
2
g) in H O (0.5 mL), followed by the addition of tri-n-
2
ed, followed, after 10 min, by addition of Et N (140 mL, 1 mmol).
3
butylphosphine (0.5 mmol). The reaction mixture was
poured in EtOAc (10 mL); Na SO was added under stirring
The reaction was monitored by TLC (Glass supported silica gel
plates; eluent: EtOAc–PE, 5:95). After about 1.5 h, the aqueous lay-
er was extracted with EtOAc (3 × 15 mL). The combined organic
2
4
to remove H O, filtered and washed with EtOAc (3 × 5 mL).
2
The organic solvent was removed under reduced pressure.
extracts were dried (Na SO ) and the solvent removed under re-
2
4
The residue was washed with n-hexane, dried, and dissolved
duced pressure. The crude material was purified by flash
1
in CDCl : H NMR (CDCl ): d = 0.86 (3 H, t, J = 7.0 Hz),
3
3
chromatography15 [silica gel 60, 230–400 mesh; sample loading
0.96 (9 H, t, J = 6.8 Hz), 1.20–1.23 (16 H, m), 1.31 (3 H, t,
(
mg)/column diameter (mm): 100/10; eluent: EtOAc–PE, 5:95] to
J = 6.8 Hz), 1.30–1.45 (2 H, m), 1.45–1.55 (12 H, m), 1.55–
remove unreacted aldehyde, phosphinoxide and afford the desired
product.
1
4
.70 (2 H, m), 2.40–2.50 (6 H, m), 3.79 (2 H, d, J = 13.2 Hz),
.01 (2 H, t, J = 7.5 Hz), 4.20 (2 H, q, J = 6.8 Hz).
(
11) All products were isolated by flash chromatography. Their
Typical Procedure for Reactions in Micellar System
Under stirring in open atmosphere, ethyl a-bromoacetate (1.0
purity, structure and stereoisomeric ratios (when E/Z
1
mixtures were obtained) were determined by H NMR
mmol) was added to a solution of SDS (0.10 g) in H O (1.0 mL),
2
analysis, in comparison with the literature data.
12) Zhao, H.; Cai, M. Z.; Peng, C. Y. Synth. Commun. 2002, 32,
3419.
13) Barrett, A. G. M.; Cramp, S. M.; Roberts, R. S.; Zecri, F. J.
Org. Lett. 1999, 1, 579.
14) (a) Concellon, J. M.; Concellon, C.; Mejica, C. J. Org.
Chem. 2005, 70, 6111. (b) Suri, C. S.; Marcischak, C. J.
Synth. Commun. 2005, 35, 379.
followed by the addition of tri-n-butylphosphine (1.0 mmol). After
(
(
(
5
min aldehyde (1.1 mmol) was added, followed by addition of Et N
3
(1.0 mmol). Vigorous stirring was continued for about 2 h, while the
reaction was monitored by TLC (silica gel; EtOAc–PE, 5:95).
Work-up was performed as described above.
Acknowledgment
(
15) Still, W. C.; Kahn, M.; Mitra, A. J. Org. Chem. 1978, 43,
2923.
Universita’ degli Studi di Milano and MIUR (Ministero dell’
Istruzione, dell’ Universita’ e della Ricerca) are acknowledged for
financial support (FIRB: Project code n. RBAU017KFW – FIRST).
Synlett 2006, No. 11, 1717–1718 © Thieme Stuttgart · New York